Atlantis leaves station after construction mission
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: February 18, 2008
The Atlantis astronauts undocked from the international space station today, looped around the outpost to collect spectacular pictures and video and then pulled out ahead of the lab complex before starting a final heat shield inspection to clear the way for re-entry and landing Wednesday.
Using a laser scanner and high-resolution camera on the end of a boom attached to the shuttle's robot arm, the astronauts carried out out a detailed survey of the ship's reinforced carbon carbon nose cap and wing leading edge panels, which experience the most extreme heating during re-entry, to look for any signs of damage that might have occurred since a similar inspection just after launch Feb. 7.
"We cleared Atlantis' heat shield from the flight day two ascent inspections," Flight Director MIke Sarafin said today. "RIght now, we're looking to see if there were any orbital debris impacts along the reinforced carbon carbon. The imagery right now is in the process of being analyzed and we should have an answer from the imagery and engineering experts within the next day."
Nothing obvious could be seen in downlinked video and assuming no problems turn up in the analysis, the crew will pack up and test Atlantis' re-entry systems Tuesday before landing Wednesday at the Kennedy Space Center. Entry flight director Bryan Lunney, son on legendary Apollo flight director Glynn Lunney, will discuss NASA's landing strategy Tuesday at a 12:30 p.m. news briefing.
This morning's forecast from the Spaceflight Meteorology Group at the Johnson Space Center in Houston predicts virtually ideal weather at the Kennedy Space Center for the first landing opportunity Wednesday with scattered clouds at 3,000 and 30,000 feet and light winds from the northeast. A slight chance of showers within 30 nautical miles is expected at Edwards Air Force Base, Calif.
"The crew tomorrow will be preparing the cabin for re-entry and just making sure that any stowage items aren't loose during the re-entry timeframe," Sarafin said. "They will prepare a special seat for (returning space station astronaut) Dan (Tani), who has been on station for about four months. ... Tomorrow, the crew will also check out the flight control systems to make sure that they're healthy and there are no problems that occurred over the course of the mission."
The shuttle has enough on-board supplies to stay in orbit until Friday if necessary, officials said. NASA normally would concentrate solely on Florida the first landing day, waving off for 24 hours if bad weather or some other problem forced a delay.
But agency officials announced last week that NASA's backup landing site at Edwards will be staffed Wednesday and for an attempt to get Atlantis down on one coast or the other, weather permitting. NASA said in a statement the strategy is intended to "give the military the biggest possible window and maximum flexibility to ensure the success" of an attempt to shoot down a falling spy satellite.
The National Reconnaissance Office satellite (NROL-21) malfunctioned shortly after launch in December 2006. The out-of-control satellite has been slowly descending ever since and barring intervention, it is expected to plunge back into the thick lower atmosphere early next month.
Because the satellite failed so soon after launch, it is carrying a virtually full load of now-frozen hydrazine rocket fuel, a good portion of which could be expected to reach the ground after a normal atmospheric breakup. The Pentagon last week announced plans to fire a missile at the spacecraft in an attempt to break it apart and disperse the toxic fuel before it can pose a threat.
The Heavens Above website is providing tracking maps showing the satellite's current location based on observations by a network of amateur satellite observers.
Atlantis commander Steve Frick and his crewmates will have two opportunities on successive orbits to land in Florida Wednesday and two shots at Edwards Air Force Base in California's Mojave Desert. Here are updated landing times for all four opportunities (in EST/GMT and mission elapsed time; best viewed with a fixed width font):
ORBIT.EVENT...................................DD/HH:MM...EST........GMT WEDNESDAY, FEBRUARY 20 202...1st KSC OPPORTUNITY DEORBIT BURN........12/17:16...08:01 AM...13:01 203...1st KSC OPPORTUNITY LANDING.............12/18:22...09:07 AM...14:07 203...2nd KSC OPPORTUNITY DEORBIT BURN........12/18:52...09:37 AM...14:37 204...2nd KSC OPPORTUNITY LANDING.............12/19:57...10:42 AM...15:42 204...1st EDW AFB OPPORTUNITY DEORBIT BURN....12/20:22...11:07 AM...16:07 205...1st EDW AFB OPPORTUNITY LANDING.........12/21:27...12:12 PM...17:12 205...2ND EDW AFB OPPORTUNITY DEORBIT BURN....12/21:58...12:43 PM...17:43 206...2ND EDW AFB OPPORTUNITY LANDING.........12/23:02...01:47 PM...18:47
"We will do our best to land Wednesday, either at the Kennedy Space Center or at Edwards Air Force Base," Sarafin said. "There is always the possibility that we could have a technical issue or some other problem occur that would cause us to not attempt to deorbit on Wednesday. We would just work that on a case-by-case basis."
But because of the time required to prepare the shuttle for re-entry, the 90 minutes it takes to go around the world for a second chance and the time needed to back out if entry is delayed for the day, NASA is unlikely to take advantage of all four possible Wednesday landing opportunities.
"A normal day, just to do a deorbit prep and landing is five hours," Sarafin said. "That doesn't account for just standard crew wakeup activities and cabin stow. If we're going to try multiple attempts, it takes another 90 minutes to go around and if we're going to do three or four orbits, that really does extend the length of the (crew's) day considerably. ... If you still cannot land and you have to back out, open the payload bay doors, turn off all the navigational aids, it does become a significant driver in decision making."
Based on past practice, assuming a reasonably favorable forecast, NASA likely would make two back-to-back attempts to land in Florida and then pick the more favorable of the two Edwards opportunities if the shuttle could not make it back to Kennedy. But if the current forecast holds up, Frick and his crewmates should have a good chance of bringing Atlantis back to Florida as planned.